Restarter.java

import org.apache.commons.lang.Validate;  
   
public class Restarter {  
   
     private final IMessagingClient messagingClient;  
     private Status status;  
   
     public Restarter(IMessagingClient client) {  
         Validate.notNull(client, "Messaging client must be specified");  
         this.messagingClient = client;  
     }  
   
     public void restart(Status newStatus) {  
         if (isTransistionFromFailureToStarted(newStatus)) {  
             messagingClient.stop();  
             messagingClient.start();  
         }  
     }  
   
     private boolean isTransistionFromFailureToStarted(Status newStatus) {  
         if (null == status) {  
             status = newStatus;  
             return false;  
         }  
   
         if (Status.FAILED == newStatus) {  
             status = newStatus;  
         }  
   
         boolean isTransitionFromFailure = (Status.FAILED == status) && (Status.STARTED == newStatus);  
         if (isTransitionFromFailure) {  
             status = newStatus;  
         }  
   
         return isTransitionFromFailure;  
     }  
   
 }